Northstar Engines and System Technical Discussion Discussion, do you need premium gas in a 4.6 nothstar in Cadillac Engine Technical Discussion; hi i found a near perfect cadillac deville concours 1999 i was wondering if you have to run premium fuel ...

Re: do you need premium gas in a 4.6 nothstar

Interesting... Curious as to why you do this tateos.

Up here in the NE we get a "special" winter blend, no choice about it. Only thing I can see is that it kicks the MPG down a notch to reduce emissions. That makes no sense in my mind, burn more to reduce emissions, but that what the oil moguls are doing under EPA direction. K_C

Re: do you need premium gas in a 4.6 nothstar

Maybe he's playing perceived combustion chamber and inlet air temperature against the slower combustion speed of a higher octane fuel.

Good ol' "If you can dream it, we can tax it" Maryland used to change MTBE mixes with the seasons. Now the environmental bureaucracy powers, in their infinite wisdom, force the counties around the pollution centers of Bawlmer and DC to run exclusively ethanol crap. And so you burn more fuel to lower the emissions which the Fed measures.

Re: do you need premium gas in a 4.6 nothstar

krimson_cardnal - I am originally from Boston, so I know about that nice 93 octane Premium you have - we only get 91 here.

I run Premium during the summer because the tendency to knock is much greater when it is 110-115 degrees out. Also, the coolant temp is higher in the summer because the AC is on and the AC condenser is in front of the radiator; also, there is more of a load on the engine because the AC compressor is sucking power off the engine - that lead to detonation - also I need the extra power since the AC is one.

Re: do you need premium gas in a 4.6 nothstar

Originally Posted by submariner409

Good ol' "If you can dream it, we can tax it" Maryland used to change MTBE mixes with the seasons. Now the environmental bureaucracy powers, in their infinite wisdom, force the counties around the pollution centers of Bawlmer and DC to run exclusively ethanol crap. And so you burn more fuel to lower the emissions which the Fed measures.

Not a bad way to keep those Oil Profits at Historic Levels either. At least the N* will accept the lower Octane. I'm a believer in the Top Tier Shell produces. Unfortunately I need to go 35m into Massachusetts to fetch it, hardly worth it, however, with the taxes NY put on top of the Feds it's almost a break even ride. K_C

Re: do you need premium gas in a 4.6 nothstar

.............but look at tateo's post on temps, load, and octane. It makes perfect sense, but if the knock sensor will detune the timing and you can live with somewhat reduced performance, you can happily burn just about anything anytime. (If I know I'm headed for a couple of speed runs or rough road driving, I squeeze in some 93..........)